Field of the invention
[0001] The invention relates to an improvement in the process of wrapping a plastic outer
packaging material under tension around an array of packs of compressible flexible
articles to form a tension wrapped unit.
Background of the invention
[0002] It is widely known in the art to package an array of packs comprising compressed
flexible articles encased in flexible bags in corrugated paper outer cases for ease
of handling, storage and transport. The space, however, inside these corrugated paper
outer cases cannot be fully utilised because of the tolerances imposed by the variations
in the pack dimensions resulting from the production processes and the usual automatic
mechanical packaging systems. The problem of utilisation of space is becoming more
and more important with the increasingly widespread use of pallets of standard dimensions
arising from the demands of large manufacturing, distribution and sales organisations.
Furthermore, due to the deviations in the pack dimensions arising from the packing
of compressible flexible articles into flexible bags, the cardboard cases need to
be over-dimensioned. As a consequence of this over-dimensioning, arrays of packs on
the bottom of pallets are incapable of supporting the imposed loads when pallets of
products are stacked or grouped three pallets high. Therefore, the cardboard cases
must be designed to support the extra loads.
[0003] An array of packs of compressed flexible articles can also be wrapped in plastic
foil. The plastic foil can comprise relatively inexpensive materials such as polymeric
films or thermoplastic films. Such materials reduce the severity of the disposal problem
from an environmental standpoint both with respect to the amount of wrapping material
required and the disposability/degradability of the particular wrapping material.
In addition, plastic foil is lighter and more flexible than corrugated paper, which
is heavy, requires space and has less flexibility for storage since it is rigid and
in use continues to occupy the same amount of space even when nearly empty.
[0004] Prior art developments include EP 0 294 339 A2 which discloses a machine for packaging
a plurality of articles, either loose, collected on a tray or inside a container,
within a stretchable or a semi-stretchable type of film web. The machine includes
a stretching device, a wrapping device and a complete sealing unit. In particular,
the invention teaches a segment of stretched and tensioned film web that is wrapped
peripherally around the articles by pushing the film web underneath the articles and
by displacing the support plane of the articles and eventually replacing it with two
roller tables associated with the wrapping device. The invention takes advantage of
the elastic memory of the film web to tightly enclose the packaged articles rather
than using the compressibility of the articles with the aid of a pusher clamp and
pusher plate to form a tight tension wrapped unit.
[0005] US 3,910,011 claims an apparatus for and a method of packaging stacked articles in
a shipping container. The apparatus comprises a means for peripherally confining a
bundle of articles in an open-ended sleeve of heat shrinkable film while leaving the
surface portions of the bundle of articles accessibly exposed. The cooling of the
heat shrinkable film produces a relatively rigid package. Similarly, US 3,672,116
discloses an apparatus and a method for wrapping a film about four sides of an object
or stack of objects; the film having sufficient elasticity to stretch without bursting.
Both patents focus on the stretch properties of the films in order to
guarantee unit stability and furthermore, wrapping is only around a circumference
of the bundle/object(s).
[0006] Therefore, the prior art does not teach a wrapping process which comprises tensioning
in two directions using a plastic outer packaging material; which is independent of
fixed dimensioned cases; which relies on the compressibility of the array of flexible
packs of compressible flexible articles in combination with a pusher clamp and pusher
plate to produce a stable unit; which is independent of the stretch properties of
the plastic outer packaging material; and which utilises a curved pusher plate that
is in close proximity to the pusher clamp.
Objectives and summary of the invention
[0007] The object of the present invention is to wrap an array of packs of compressed flexible
articles under tension in two directions using a plastic outer packaging material
to form a tension wrapped unit. A further object of the invention is to prevent the
distortion and deformation of the corners of the array of packs of compressible flexible
articles when being wrapped under tension with the plastic outer packaging material.
[0008] The invention utilises process steps that encompass modifications in order to produce
a tension wrapped unit comprising a plastic outer packaging material, which is most
suitable as a replacement for conventional corrugated paper outer cases. The process
originally was employed to wrap arrays of individual flexible articles to form primary
wrapped packs with the aid of a pusher clamp and a pusher plate. The array of articles
were tension wrapped in one direction only and the pusher clamp simply pushed the
array of articles to a fixed point where the wrapping process was initiated. The resultant
primary wrapped packs could be easily distorted and deformed and in addition, the
compressibility of the flexible articles was not utilised to form a more stable pack.
The present invention is directed towards the wrapping under tension of arrays of
primary wrapped packs of compressible flexible articles to form completely enclosed
units.
[0009] During the wrapping process, the inherent compressibility of the arrays of packs
of compressible flexible articles with the aid of the pusher clamp and pusher plate
can be taken advantage of to tightly wrap the plastic outer packaging material around
the entire array in two directions. This imparts increased stability and strength
to the unit. Furthermore, key design optimisations - the use of a pusher plate that
is curved and is in close proximity to the pusher clamp - have been incorporated into
the process. These features have subsequently led to several benefits namely, units
that are more stable and that are capable of sustaining higher load carrying capacities;
better unit shapes; improved unit appearances and improved and optimised pallet fit
during handling, storage and transport operations results.
[0010] In accordance with the objects of the invention, a unit comprising an array of at
least one substantially parallelepipedal pack comprising compressed flexible articles
is provided. The unit has a top and a bottom panel, a front panel and a back panel
and two side panels and comprises a plastic outer packaging material. The pusher clamp
pushes the array towards the plastic outer packaging material consisting of two sheets
sealed at the centre. The plastic outer packaging material has a width dimension that
extends beyond the transverse limits of the array and it is disposed adjacent to the
front, top and bottom panels of the array. The array is maintained in a fixed position
by the action of a pusher plate and by resting on a base plate. The pusher clamp then
retreats and guide rollers ensure that the plastic outer packaging material is disposed
adjacent to the back panel. It can then be gathered, sealed and cut. The array is
compressed in a direction of compression C by means of the pusher clamp and is pushed
in a direction perpendicular to the direction of compression C' by the pusher plate.
The plastic outer packaging material extending beyond the transverse limits of the
array is disposed adjacent to the remaining side panels of the array and then gathered,
folded, sealed and cut. The unit may comprise a least one unobstructed opening feature
in the plastic outer packaging material.
[0011] The pusher plate is curved at the edges and comprises a radius ranging from 5 to
30 millimetres and an angle A ranging from 30 to 90 degrees. The distance H from the
top of the pusher clamp to the bottom of the pusher plate ranges from 0 to 50 millimetres.
[0012] According to the present invention, the objects are achieved by a pusher plate having
the characteristics specified in the claims.
Brief description of the drawings
[0013] The invention will be described hereinafter with reference to the following drawings:
Figure 1 is a perspective view of an array of flexible packs being compressed by a
pusher clamp in the direction of compression C;
Figure 2 shows a front elevation of the partially wrapped array of packs supported
on a base plate and being held in tension by a curved pusher plate;
Figure 3 shows a front elevation of an array of packs after the pusher clamp has retreated
and at the point when the plastic outer packaging material is being gathered together;
Figure 4 shows the front elevation of the curved pusher plate.
Detailed description of the invention
[0014] Figure 1 shows an array
11 comprising at least 1 substantially parallelepipedal pack
12. In particular, figure 1 details two substantially parallelipedal packs
12. Each pack
12 is enclosed in a flexible bag and comprises compressed flexible articles. The array
11 is compressed by means of a pusher clamp
13 in the direction of compression
C. The compressed flexible articles may comprise disposable absorbent diapers, sanitary
articles, incontinent pads or briefs, bandages and the like. The flexible articles
are compressed to between 20 and 70 percent of their uncompressed volume. Each flexible
pack
12 comprises between eight to fifty disposable absorbent diapers and a flexible plastic
bag with a thickness ranging from 30 to 120 micrometres. A method for the compression
packing of disposable absorbent diapers into flexible bags has been described in detail
in the following patents US 4,934,535, US 4,966,286, US 5,022,216, US 5,050,742 and
US 5,150,561.
[0015] According to figure 1, the array
11 of packs
12 of compressed flexible articles comprises a top panel
14, a bottom panel
15, a front panel
16, a back panel
17 and two side panels
18,
19. The pusher clamp
13 is disposed adjacent to the side panels
18,
19 and to the back panel
17 of the array
11. The pusher clamp
13 pushes the array
11 towards the plastic outer packaging material
20. The plastic outer packaging material
20 comprises two sheets of film, fed from two infeed rollers
21, which are sealed at the centre. The width dimension of the plastic outer packaging
material
20 extends beyond the transverse limits of the array
11 to be wrapped. The preferred material for the plastic outer packaging material
20 is a polyethylene film, which can either be of a low, medium or high density. More
specifically, the film has a thickness ranging from 30-100 micrometres; 50 micrometres
being preferred. The film can either be transparent or white and thus, various combinations
for the array
11 of packs
12 are possible. In addition, the film may comprise graphical indicia, which can also
be coloured. The plastic outer packaging material
20 is disposed adjacent to the front panel
16, the top panel
14 and the bottom panel
15 of the array
11 and maintained in tension by the pusher clamp
13. The pusher clamp
13 compresses the array
11 in the direction of compression
C and ideally, the circumference of the array
11 is reduced by a figure in the range from 2-20 percent; 5 percent being preferred.
[0016] Figure 2 shows the plastic outer packaging material
20 wrapped tightly against the front panel
16, the top panel
14 and the bottom panel
15 of the array
11. The array
11 is subsequently maintained in a fixed position by resting on a base plate
22 and by the action of a curved pusher plate
23. The curved pusher plate
23 is disposed adjacent to the top panel of the array
11 and compresses the array
11 from above in the direction of compression
C'. The circumference of the array
11 around the side panels
18,
19 is reduced by approximately 2-8 percent; preferably by 5 percent. The array
11, which is partially wrapped, is still being subjected to a side compression from
the pusher clamp
13.
[0017] In figure 3, the pusher clamp
13 retreats and the guide rollers
24 ensure that the plastic outer packaging material
20 is pulled under tension and disposed adjacent to the back panel
15 of the array
11. The plastic outer packaging material
20 is subsequently gathered, sealed and cut. The seal may comprise a straight seal.
In order to gather the plastic outer packaging material
20 to form the tight seal, some of the compression of the array
11 may be lost, but this is minimal and is about 2-4 percent. Upon cutting, the outer
plastic packaging material
20 is released from the array
11 and is available for wrapping around the next array
11 of packs
12. The plastic outer packaging material
20 extending beyond the transverse limits of the array
11 is pulled around and disposed adjacent to the remaining side panels
18,
19 of the array
11. The plastic outer packaging material
20 is then gathered, folded, sealed and cut. The side seal may either be folded or comprise
a straight seal. As before, the cutting step is not essential. The end product is
a tension wrapped unit
10.
[0018] Figure 4 shows the front elevation of the pusher plate
23. The pusher plate is typically characterised by a flat surface and its dimensions
are usually smaller than the array of packs to be wrapped. The new design is based
on a curved surface and is designed to fit the dimensions of the array
11. This modification results in a much higher level of compressed matter being retained
within the array
11 since the uppermost corners of the array
11 are contained. Furthermore, the pusher plate is placed in close proximity to the
pusher clamp
13 in order to provide for a much tighter tensioned wrapped unit
10. By placing the pusher clamp
13 close to the pusher plate
23, a reduced level of excess compressed matter can escape when gathering and sealing
the panels
17,
18,
19. Usually, the excess compressed material held in compression by the flat surfaced
pusher plate could be easily squeezed out through the free space located at the corners
of the primary wrapped packs.
[0019] The radius
R of the pusher plate can range from 5 to 30 millimetres though 20 millimetres is the
preferred radius. The angle
A ranges from 30 to 90 degrees with 60 degrees being the preferred angle. The distance
H from the top of the pusher clamp
13 to the bottom of the pusher plate
23 can vary from 0 to 50 millimetres with 5 millimetres being the preferred distance.
[0020] In relation to all the figures, the plastic outer packaging material
20 may comprise an unobstructed opening feature
25, which is readily located and which can be easily and reliably opened in order to
gain easy access to the packs
12 within the array
11 of the unit
10. The unobstructed opening feature
25 is included in order to provide a more controlled release of the compressive forces
acting on the compressed flexible packs
12. The plastic outer packaging material
20 comprises at least one unobstructed opening feature
25, which may comprise a predetermined tear portion in the form of a line of weakness.
Lines of weakness can be formed by many means well known in the art and typically
comprise, for example, perforations. The lines of weakness may be produced on-line
or they may be already present in the plastic outer packaging material
20 as provided by the suppliers. Thus, the unobstructed opening feature
25 comprises a line of weakness, which may traverse the circumference of the entire
unit
10 in either the horizontal or vertical plane or which either may traverse the top panel
14 or the bottom panel
15 of the unit
10 or which either may traverse the top panel
14 and part of the side panels
18,
19 or the bottom panel
15 and part of the side panels
18,
19. In addition, graphical indicia may be provided on the plastic outer packaging material
20 to highlight the location of the unobstructed opening feature
25.
[0021] For the purposes of transport and storage, a number of units
10, each unit
10 preferably comprising two to twelve packs
12, can be stacked or grouped in a plurality of configurations on a pallet such that
a load is applied to an upper panel or to a side panel of the pallet configuration
with the direction of the load being perpendicular to the direction of compression,
which is around the circumference of the pallet configuration. The units
10 are less compressible in directions perpendicular to the direction of compression.
Glossary
[0022]
- 10
- unit
- 11
- array
- 12
- pack
- 13
- pusher clamp
- 14
- top panel
- 15
- bottom panel
- 16
- front panel
- 17
- back panel
- 18, 19
- side panels
- 20
- plastic outer packaging material
- 21
- infeed rollers
- 22
- base plate
- 23
- pusher plate
- 24
- guide rollers
- 25
- unobstructed opening feature
1. A process for producing a tension wrapped unit (10) comprising an array (11) of at
least 1 substantially parallelepipedal pack (12) wherein a pusher clamp (13) is disposed
adjacent side panels (18, 19) and back panel (17) of said array (11), said pusher
clamp (13) pushes said array (11) towards a plastic outer packaging material (20)
comprising two sheets of film sealed at the centre wherein width dimension of said
plastic outer packaging material (20) extends beyond transverse limits of said array
(11), said plastic outer packaging material (20) is disposed adjacent front panel
(16), top panel (14) and bottom panel (15) of said array (11), said array (11) is
subsequently maintained in a fixed position by the action of a pusher plate (23) and
by resting on a base plate (22), said pusher clamp (13) retreats and guide rollers
(24) ensure said plastic outer packaging material (20) is disposed adjacent said back
panel (17),
characterised in that
said array (11) is compressed in a direction of compression C by means of said pusher
clamp (13) and compressed in a direction perpendicular to said direction of compression
C' by said pusher plate (23), said plastic outer packaging material (20) extending
beyond transverse limits of said array (11) is disposed adjacent said remaining side
panels (18, 19) of said array (11).
2. A process according to claim 1 wherein said plastic outer packaging material (20)
disposed adjacent said back panel (17) is gathered, sealed and cut.
3. A process according to any of the previous claims wherein said plastic outer packaging
material (20) disposed adjacent said remaining side panels (18, 19) of said array
(11) and is gathered, folded, sealed and cut.
4. A process according to any of the previous claims wherein said pusher plate (23) said
is curved at the edges to contain said array (11).
5. A process according to any of the previous claims wherein said pusher plate (23) comprises
a radius ranging from 5 to 30 millimetres and an angle A ranging from 30 to 90 degrees.
6. A process according to any of the previous claims wherein the distance H from top
of said pusher clamp (13) to bottom of said pusher plate (23) ranges from 0 to 50
millimetres.
7. A process according to any of the previous claims wherein said plastic outer packaging
material (20) comprises at least one unobstructed opening feature (25).
8. A process according to any of the previous claims wherein said pack (12) may comprise
disposable absorbent diapers, sanitary articles, incontinent pads or briefs, bandages
and the like.